This Friday, September 18, is Park(ing) Day, when people across the nation (and the world) turn metered parking spaces into temporary parks. The event, which we've previously covered and in which we've participated, was conceived in 2005 by the San Francisco-based art collective Rebar in 2005, when members who were dismayed at the inordinate amount of public space that's wasted on cars spent a day feeding the meter beside a parking spot and using the land as a temporary park. Since then, participation has spread like crazy, and the annual event now includes all sorts of festivities.There's a great slide show of past park set-ups here, and we encourage people far and wide to take part.